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2355 - different entries in tag "Camera Lens" for the same lens


Uwe
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Hello,
there are different entries in the tag "Camera Lens" for the same lens. Here is the explanation and a request:
1. a RAW photo is imported (e.g. Canon CR2 format). Daminion first reads the tag "LensType" from the "MakerNote". This leads to the following tag content of Camera Lens in Daminion: "Canon EF 24-70mm f/2.8L II USM".The tag "Exif:LensModel" with the content "EF24-70mm f/2.8L II USM" is also present, but is not considered because of the priority when reading (see Daminion Mapping Rules).
2. The RAW photo is opened with the RAW converter in Photoshop CS6 and only the lens correction is performed. This creates an XMP sidecar file that only contains the tag "XMP-aux:Lens" with the following content: "EF24-70mm f/2.8L II USM".
3. The CR2 RAW file is exported as a TIF and imported into Daminion. In the TIF file the tags "Exif:LensModel" with the content "EF24-70mm f/2.8L II USM" and "XMP-aux:Lens" with the content "EF24-70mm f/2.8L II USM" are present. According to the mapping rules, "XMP-aux:Lens" is read.
4. from 3. follows: thus two entries of the same lens are present in the tag "Camera Lens":
from the CR2 RAW: "Canon EF 24-70mm f/2.8L II USM" and
from the TIF file: "EF24-70mm f/2.8L II USM".
5. if, however, the RAW file is now read again using "Read tags from file", the tag from the "Maker Note - LensType" of the CR2 file is not read, but the tag "XMP-aux:Lens" from the XMP sidecar file and thus the content of the tag "Camera Lens" of the CR2 RAW file in Daminion becomes "EF24-70mm f/2.8L II USM".
Conclusion:
I.e. As long as the original RAW file (with existing XMP sidecar) is not read again via "Read tags from file", different entries exist in the tag "Camera Lens" for the same lens.
Please:
Either Daminion changes the order of priorities when reading, first "Exif:LernsModel" or better in one of the settings files the user can set the order himself.
Many greetings, Uwe

Update: here is an example how one can set the priority for tag in digiKam (Linux version)

 

Read_priority.jpg

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  • 3 months later...

Hello,

I found in the German Wiki https://de.wikipedia.org/wiki/Metadata_Working_Group the following example description for JPG files (translated by Deepl.com):

"Up to now, in a digital image file, for example in JPG format, different information on the same subject can be stored simultaneously in the containers for Exif as well as for IPTC and XMP. It is undefined which information is valid.

With the MWG specification, it is clearly defined for the example JPG file that the Exif information has priority over IPTC and XMP, provided that it is present here."

From my point of view Daminion should read Exif metadata first, even if in the settings of the preferences the sidecar is selected for RAW files to get the unique metadata in the catalog independent on the time the files was read.

Regards, Uwe

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